After a call for tender, ASA astrosystem was chosen to provided us 3 telescopes 600mm Ritchey-Chretien with their mounts. Mounts use the direct drive technology to allow the best performances in terme of traking, pointing and capacity of load. A special corrector is ongoing design to match with our specifications in term of telecentricity, image quality and field of view.

First telescope installed at ExTrA observatory

Guiding Camera

To improve the guiding of the mount , we use a guiding camera with a large detector. The large size allow to use more star and makes sure that we have a star in the field of view. But to have a good precision we need small pixels. That why we have chosen the FLI Microline ML4070 camera.

Focale Plane

It's an importante part of the project. Here the light is pick up with fiber to go to spectrometer and scientific caméra. To exectute that we need precision and repetability.
After a call for tender, the attocube's ECS3080 linear stage was choosen for it's extrem precision and large travel. With a XY construction and 5 modules we can cover all the field of view provided by telescope. Each module is composed by: 2 linear stages ECS3080, one arm, and 2 bundle of fiber (science and positionning).
The focal plane is composed by 5 modules (1 for Science and 4 for star comparizon). For each field of view, the stages moves to align precisely fiber with a selected star. Behind, the guiding camera ML4070, can see with an special optic each arm to know where they are precisely.

3D view of the focal plane


The infrastructure will be composed by three domes and a container. Here you have a "3D rendering" of the project.

plan of observatory artist view of the project
Picture of the extra observatory with three domes

The dome

After prospection and some visit of differents observatories, we have choice (after a call for tender too) the ScopeDome manufacturer's dome. Here after the specification:

The sky camera

We have choice the Starlight Xpress Ltd Oculus (180 lens) to watch the sky and know if clouds are comming soon. It is an important device to protect telescopes and devices in a remote observatory.

Science Camera

The scientific camera is an important part of this project. Lot of attention was done in the choice of the detector. After prospection and a call for tender, we choosed NIRvana_LN detector of Princeton Instrument.


The spectrometer is in front of the science camera. This part collects all the fibers, and with different opticals parts, image the fibers outputs on the camera with some wavelengths bands.
This part is important to increase the sensibility of the instrument.
The spectrometer is composed of two way. One scientific ligne and one other to help to center the star on the fiber.
All the spectrometer is cool down to improve the possibility to work on infrared wavelengths.

view of spectrometer 1
view of spectrometer 2


The location of the ExTrA Facility is at La Silla Observatory under Dutch Telescope. As an infrared instrument dedicated to photometric time-series, ExTrA requires the driest and darkest site, with the greatest number of consecutive clear nights. ESO proposed this site to match with our specifications.

aerial view of Paranal Observatory